Article of manufacture and preparation thereof



Nov. 19, 1935.

F. H. MANCHESTER ARTICLE OF MANUFACTURE AND PREPARATION THEREOF FiledFeb. 14, 1935 fiqnf/f/Yancesfer Patented Nov. 19, 1935 ARTICLE OFMANUFACTUR EAND PREPARATION THEREOF Frank H. Manchester, Akron,hio,.assignor to Wingfoot Corporation. Wilmington, Del., a corporationof Delaware Application February 14, 1935, Serial No. 6,511

12 Claims. (Cl. 51-190) This invention relates to improved articles ofmanufacture and particularly to surfacing apparatus. such as rolls,wheels, face grinders and belts, adapted for 'abrading and polishing,and

to the method of preparing such improved articles of manufacture. Itespecially concerns s rfacing devices in which the abrading or polishing surfaces are supported upon resilient rubber cushion or bases. Anobject of the invention is to provide an improved article of manufacturecomprising rubber and subdivided material attached thereto. Another isto provide a surfacing element which is eflicent, long-wearing andinexpensive. Still another object is to provide an improved bond betweenthe resilient rubber cushion and the abrasive layer of a surfacingelement-particularly, in devices in which the abrasive layer issubstantially inelastic. A further object is to provide a cushionedpolishing device which may have either a convex or concave surface andstill be eflicient and long-wearing. It is a still further object of theinvention to provide a polishing roll or wheel having a substantiallyuniformly true body of resilient rubber about the roll or wheel axle andto the surface of which a number of applications of glue and abrasivemay be firmly adhered from time to time without adversely affecting theresilient rubber body. Another object is to provide an a method ofpreparing the improved articles of manufacture of the invention. Otherobjects and advantages will become apparent as the description of. theinvention proceeds.

Cushioned surfacing elements have been known heretofore. For instance,wheels with cloth or felt cushions have been used extensively. Thosewith cloth cushions polish neither as swiftly nor as efliciently asthose with rubber cushions while those'with felt'are more expensive thanthose 40 with rubber. In the, field of rubber cushioned wheels and rollsone difficulty has been that of satisfactorily bonding the abrasivematerial to the rubber. The abrasive material is most generally attachedto the wheel or rollby means of glue or other inelastic proteinadhesive. Glue, however, as well as other such adhesives, does notadhere directly to rubber successfully, especially when the rubber isdeformed, but spalls or chips oil after a short period of use.

one improvement in rubber surfacing elements whichhas been fairlysatisfactory is that described in United States Patent No. 1,963,357 toE'. A. Fiiley. Therein one or more layers of fabric are secured to-therubber body and the abrasive as -=material is bonded to the fabric.Another improvement is that described in my application Serial No.700,832, filed December 4, 1933, wherein is set forth an abrasive devicecomprising rubher to which the abrasive and glue layer is bonded by aprotein-latex composition.

While these referred-to improvements are in general satisfactory, thisinvention comprises a discovery which is even more satisfactory. Brieflystated, it involves an improved resilient rubber-subdivided materialcomposite article in which the subdivided material is more firmlybondedto the resilient rubber than'has been possible heretofore. It isof particular value where the layer of subdivided material issubstantially inelastic. As applied to a surfacing element, it comprisesthe provision between the body of resilient rubber and abrasive materialof a layer which is substantially inelastic and contains an irregularpatch work of very small fissures. For a. better understanding of theinvention, reference-- may be had to the accompanying drawing where'-in:

Fig. 1 is a side elevational view of a polishing roll embodying thefeatures .of the invention in which various layers are broken away tomore clearly illustrate the construction;

Fig. 2 is an end elevational view of the rollof' Fig. 3 is an elevationof a polishing wheel embodying the features of the invention and show- Iing one form of a wheel which the invention makes possible;

Fig. 4 is a cross-sectional view of the wheel shown in Fig. 3 takenalong theline IV-IV;

Fig. 5 is an end elevational view of a polishing wheel with adifferently shaped surface from that shown n Fig. 3; e

Fig. 6 is an enlarged, fragmentary view show-*-- ing the features of theinvention as well as an. alternative feature which may be embodiedthere- 40 in; and

Fig. 7 is a more enlarged, fragmentary view than Fig. 6 showing moreclearly the features of v the invention.

The principles of the present invention are applicable particularly torubber cushioned polishing wheels and rolls but extend to other rubbercushioned surfacing elements such as, for example, belts and facegrinders and also to any article of manufacture comprising resilientrubber to which is attached an inelastic layer of subdivided material.One type illustrated in Figs. 1 and 2 is a roll adapted for polishing orgrinding surfaces of considerable area. In this embodiment, thepolishing roll may be of considerable I length, varying from six inchesto six feet, or

prises an irregular patch work of very small fismore, depending upon theuse to which it is put. The diameter of the roll also may be widelyvaried, depending also upon the use for which it is designed.

In the roll shown in Figs. 1 and 2 there is comprised a shaft l5 andflanges or end plates l6 which may be secured to the shaft l5 or may beformed integrally therewith. Between the flanges l6 and encircling andsecured to the shaft l5 by a hard rubber layer or other attaching meanswell known in the art is a body of resilient rubber l1 forming acushion. It will be appreciated that the composition and resiliency ofthe rubber body I1 is dependent upon the grinding operation to beperformed and may be of any degree of softness or stiffness whichfunctions best in the adaptation to which the wheel is put. It will alsobe understood that while the word rubber applies preferably to theordinary form derived from the Hevea Brasiliensis tree, including, ofcourse, the usual compounding ingredients, it. also comprises syntheticvulcanizable resilient materials, generally termed synthetic rubber, ofwh h Du Prene is an example.

On the outside of the body of resilient rubber I1 is a thin layer 20,preferably of treated rubber, which is substantially inelastic, firmlyadhere'nt to the'rubber body I! and which comsures. To the layer 20 isthen bonded abrasive material 22 by means of an adhesive such as glue.If desired, any number of additional coatings of abrasive materialindicated by the numeral 23 may be applied. The abrasive material may beapplied in any known manner. One method is to apply a mixture of glue orother adhesive and a suitable granular abrasive material, exemplary ofthe latter being sand, emery, carborundum, rouge, etc. The abrasivematerial mayalso be applied by c v.lng layer 20 with glue or otheradhesive and then, while the adhesive is still tacky, sprinklingthereover the abrasive material, or by rolling the device in a loosequantityof abrasive.

In the manufacture of a polishing roll embodying the invention avulcanizable resilient rubber body H is attached to the shaft l5 bymeans of' a layer of hard rubber or other bonding agent, such as. asuitable cement, between the two. The roll is then vulcanized and theperiphery of the rubber layer ll ground to a state of smoothness' andsubstantially uniform trueness. Thereupon the layer 20 is provided.

. quired for best results.

One method of preparing layer 20 is that of rotating the roll at roomtemperature in a bath of concentrated sulphuricacid (98%) for a shortperiod of time. The time required is that .suflicient to producetheeffect described and varies with the type of rubber compound comprisingthe resilient rubber body l1 and with the strength of acid used; Forinstance, with a highly loaded carbon black rubber stock the applicationof d 98% sulphuric acid requires only min- It is preferably obtained bytreating the outer surface of the provided.

ute to transform the surfacethereof to a hardened substantiallyinelastic layer which cracks on deformation to give an irregularpatchwork of very small fissures. With a soft, nearly pure gum stock ontheother hand, an application of the same acid for approximately threeminutes is required to give the desired surface layer 20. Similarly, thetime required varies with the concentration of the acid. Thus, with a hih y loaded black stock the following times of reaction are required toproduce the same effect:

Concentration of H250 Time Per cent Minutes It will also be understoodthat the reaction should be stopped as soon as a good crust (the layer20) is obtained, for further treatment chars and weakens the hardenedlayer making it somewhat friable or crumbly and not sufilcientlyadherent to the unconverted rubber underneath.

'At the completion of the treatment the acid is ll represents theresilient rubber body, 20 the.

substantially inelastic and fissured layer, and 22 the layer of abrasiveand bonding agent. The fissures in the layer 20 are shown by the numeral24 and are formed substantially immediately upon deformation of thelayer 20. If the bondingagent for the abrasive is glue or othernonextensible adhesive, on deformation of the resilient body l'l, thelayer 22 will also crack as denoted by the numeral 26. If there is noalleviating means such as is provided by the layer 20, the abrasivelayer 28 will become loosened at a the edges of the fissures 26 from theresilient body I1 and will soon chip off in flakes from said body II.will crack or check at substantially the same As noted in Fig. 7, thelayer 22' places as the layer 20, forming small sections of abrasivematerial 28 on top of small sections 30 of the layer 20 which may besaid to be in the nature of islands. The layer 20 while integrallyadherent to the rubber body 11, yet, by being fissured, permits arelatively large amount of movement of the small islands 28. Theabrasive islands 28 adhere firmly to the-islands 30 and, on deflection,such as is caused by the application of the surfacing device to somemetal article which is being polished, both islands 28 and an move asone body, thereby preventing.

the chipping off from the resilient rubber ll, of the abrasive layer 22at the fissures 26. It is readily seen that an excellent bonding betweenthe rubber body l1 and the abrasive layerv 22 is It is to be understoodthat this invention is not limited by any theories expressed herein butthat, in any event, the abrasive layer ture from the air) the roll orother polishing device at room temperature in a bath of a 2% solution oftin .etra chloride in ethylene dichloride or other solvent for a shortperiod of time. with a'highly loaded black stock a treatment of three orfour irnnutes is sufiiclent. The tin tetra chloride also renders thesurface inelastic and crackable on deformation and, in fact, gives athicker, tougher layer than sulphuric acid without rendering the layerfriable. It, however, gives arather glossy surface to which the abrasivebonding agent adheres satisfactory but not quite as strongly as to asulphuric acid treated surface. It has the advantage though of providinga somewhat stronger union between the treated layer 20 and tlieresilient rubber body H.

For a layer 20 prepared by the use of tin tetra chloride themodification shown in Fig. 6 has been i found desirable, although notnecessary, Fig.

'6 also shows an enlarged, fragmentary, cross-sectional view of asurfacing device embodying the invention. In this figure the numeral l'ldenotes may comprise an aqueous composition comprising, for example, 5%of casein and 15% of latex,

casein being in solution as ammonium caseinate. The reference to latexcontent refers to the rubber hydrocarbon present in the latex. Ifdesired, several coatings of this casein-latex composition may beappliedto the layer 20. Also, the casein and latex may be varied in anysuitable proportions, compositions comprising 5% casein and 2 latex aswell as compositions comprising caseln and 5% latex having been foundsatisfactory.

' 'Itis' also possible to use other proteins such as haemoglobin,glue,'mucin, etc. A'vulcanized latex may also be employed in thecompositions disclosed herein or a small amount of sulphur may be addedand the composition vulcanized. However, unvulcanized latex withoutsulphur is quite satisfactory. After the, one or more adhesive layers 2|is substantially dry, a coating of glue or other adhesive and anabrasive 22 may be applied as described with reference to Fig. 1.--

Another method of treatment found quite satisfactory is that of firsttreating the surface of the rubber body II with sulphuric acid fora'short period (with concentrated. H2804 and a highly loaded black stockone minute is sufficient) and thereafter treati 1;: it with a twopercent solu- 5% solution of b omine '(Bra) in ethylene dichloride orother solvent which requires a V2 min-- -ute treatment on a highlyloaded black stock to give the desired layer 20. A one percent solutionof bromine (Bra) in ethylene dichloride is also satisfactory, requiringabout one minute on' a highly loaded black stock to give the desiredeffect. Saturated chlorine in water is also a good; 5 treating agent butrequires a period of appreximately four hours to-provide the properlayer 20. Nitric acid also can be used, a concentrated (70%) nitric acidsolution requiring five minutes treatment. Other treating'agents are 50%'CIO: in it) cave surface and Fig. 5 another wheel :,with a convexsurface,'both of these shapes beingmade posas sible in a satisfactoryform for the first time by the present invention. The wheels of Figs. 3and 5 may comprise a shaft such as that described in Fig. 1 or they maycomprise a wheel with the surfacing element in the form of a thinring-in the 30 manner described in. United States Patent No. 1,963,357.

Fig. 4 is a cross-section of the wheel of Fig. 3 taken along the lineIV--IV and shows the body of resilient rubber II, the treated layer 20and the adhesive-abrasive layer 22. v f.

The invention is particularly desirable in polishing rolls or wheelswhich are used for fast, uniform polishing. As set forth hereinbefore,the

glue and abrasive layer adheres firmly to the layer 40.

20-, and, although cracked or checked" throughout its area, remainsattached to the surfacing device \IOl a much longer period of time thanhas been possible by prior art devices. Another advantage of theinvention is that the layer 20 will withstand the heating caused by thei'riction of cutting and polishingmetal articles. Still anotheradvantage "is found in the simple method provided for preparing suchsurfacing elements. As-has been disclosed, the process simply comprisesthe [in attachment of a resilient rubber body to a shaft or other base,grinding the periphery of the layer to trueness (desirable where thewheel. or roll must undergo high speed operations) immersing or rotatingthe rubber body in a treating bathfor a shortperiod of time and thenapplying the Y plicable for wheels and rolls in which thcabrasi eisbonded by means of glue, the glue b'eing-wateroe soluble and thetreated layer 20 not being affected by water. The abrasive layer whenworndm may be replaced merely by dissolving off the glue and abrasive inwater and then re-eoating-the layer 20 with more glue and abrasive. Thisprocess may be repeated from six to twenty times without the necessityfor regrinding the roll-"or wheel and re-dipping it in a treating bath.

Another advantage of the invention is found. in the fact that surfacingelements with either convex or concave surfaces may be. prepared simplyand efiiciently. Furthermore, wheels or rolls with such surfaces are'quite eflqcient and long wearing. The invention is also applicable foruse in rubber rings or sleeves containing no 76 base. The resilientrubber body may be provided with a layer 20 as provided herein and thensecured to a shaft, wheel or other base by suitable means. Also, ifdesired, one or more abrasive layers 22 may be applied prior to securingthe rubber to a base. The invention further may be employed to advantagein face grinders which are to be used for polishing articles of glassand the like. It may be employed generally in attaching inelasticsubdivided material to a resilient rubber body.

It will be understood that the fineness or coarseness of the abrasiveapplied to the surfacing elements of the invention is dependent upon thetype of work for which they are intended, and that the number ofcoatings of abrasive upon the layer 20 may be widely varied to meetdifferent requirements; Accordingly, the terms "abrasive, polishing,etc. in the claims are to be construedin their broadest sense. It willalso be understood that as an adhesive for the abrasive or othersubdivided material, in addition to glue or other proteinous material,bakelite and other thermosetting synthetic resins ,may be employed.Thermoplastic resins likewise may be used but they should have a meltingpoint suiliciently high to prevent softening dur ing use. Sodiumsilicate also is a very satisfactory substitute for glue.

Although only the preferred forms which the invention may assume havebeen illustrated and described in detail, it will be. apparent to thoseskilled in the art that the invention is not so limited, but thatvarious modifications may be made therein without departing from thespirit of the invention or from the scope of the appended claims. It isintended that the patent shall cover, by suitable expression in theappended claims, whatever features of patentable novelty reside in theinvention.

What I claim is:

1 An improved polishing device comprising a base member, a body ofresilient rubber secured to said base member, a thin layer of treatedrubber comprising the outer portion of said body of resilient rubber,said layer of treated rubber being diificultly separable from said bodyof resilient rubber, being substantially inelastic and containing anirregular patchwork of very small fissures, and a coating of adhesiveand abrasive secured to said layer,

2. In a rubber cushioning surfacing element which comprises a base, acushioning layer of resilient rubber and an outer layer of adhesive andabrasive material, the improvement which comprises a layerof treatedrubber between the resilient rubber cushion and the layer of adhesiveand abrasive, said layer of treated rubber being integrally adherent tothe body of resilient rubber, being substantially inelastic andcontaining an irregular patchwork of fissures.

3. The method of preparing an improved sur-' facing element whichcomprises attaching a resilient, vulcanized rubber body to a base,rendering the surface of said resilient rubber body substantiallyinelastic and crackable on deformation by subjecting the surface for ashort period of time to the action of a rubber conversion agent,

material to said surface.

5. An improved process for preparing a cylin- '5 drical polishingelement which comprises vulcanizing a circular body of resilient rubberto a base, grinding the periphery of the resilient rubber to substantialsmoothness and trueness. subjecting the surface of said body ofresilient 10 rubber to a rubber conversion agent for a time sufficientto convert'the surface of said body of resilient rubber to asubstantially inelastic layer which is crackable on deformation butinsuflicient to convert said surface to a friable layer, 15 and bondingabrasive material to said treated surface.

6. An improved polishing device comprising a base member, a body ofresilient rubber secured to said base member, a thin layer of treated 20rubber comprising the outer portion of said body of resilient rubber,said layer of treated rubber being difllcultly separable from said bodyof resilient rubber, being substantially inelastic and containing anirregular patchwork of very small 26 fissures, a coating of aprotein-latex composition and a coating of adhesive and abrasive securedto said layer.

7. An improved polishing device comprising a base member, a body ofresilient rubber secured 30 to said base member, a thin layer of treatedrubber comprising the outer portion of said body of resilient rubber,said layer of treated rubber being diillcultly separable from said bodyof resilient rubber, being substantially inelastic and containing anirregular patchwork of very small fissures, a coating of a casein-latexcomposition and a coating of glue and abrasive secured to said layer.

8. In the method of preparing improved rub-10 ber cushioned polishingdevices, the step which comprises subjecting the surface of theresilient rubber cushion to a rubber conversion agent for a timesufllcient to convert an outer layer of said resilient rubber cushion toa substantially inelastic layer which is crackable on deformation butinsuflicient to convert said surface to a friable layer.

9. In the method of preparing improved rubber cushioned polishingdevices, the step which comprises subjecting a surface of the resilientrubber cushion to a rubber conversion agent for a time sufficient toconvert an outer layer of said resilient rubber. cushion to asubstantially ineiastic layer which is crackable on deformation butinsufficient to convert said surface to a friable layer, said rubberconversion agent being selected from the group consisting of sulphuricacid, tin tetra chloride, bromine, chlorine, nitric acid, a mixture ofnitricand sulphuric acids, sulphuric acid containing CrOa, andhydrochloric acid containing an oxidizing agent.

10. An improved polishing device comprising a body of resilient rubber,a thin layer of treated rubber comprising an outer portion of said body05 of resilient rubber, said layer of treated rubber being difllcultlyseparable from said body of resilient rubber, being substantiallyinelastic and containing an irregular patchwork of very small fissuresand a coating of adhesive and abrasive 7o secured to said layer. a

11. An improved polishing device comprising a base member, a body ofresilient rubber secured to said base member, a relatively thin outerlayer of chemically treated rubber integral with said 76 body ofresilient rubber, said outer layer being substantially inelastic andcrackable on deformation so that fissures are formed in the surfacethereof and a coating of adhesive and abrasive applied to the outersurface of said layer.

12. An improved polishing device comprising a base member, a body ofresilient rubber secured to said base member, a thin layer of treatedrubher comprising the outer portion of said bodyof resilient rubber,said. layer of treated rubber being diflicultly separable from said bodyof resilient'rubber, being substantially inelastic and containing anirregular patchwork of very small fissures, and a coating of finelydivided material secured to said layer. I

FRANK H. MANCHESTER.

